Numerous instruments analyze the properties of captured light, or otherwise rely on light to carry signals within the instruments. As an example, a molecular spectrometer (sometimes referred to as a spectroscope) is an instrument wherein a solid, liquid, or gaseous sample is illuminated, often with non-visible light such as light in the infrared region of the spectrum. The light from the sample is then captured and analyzed to reveal information about the characteristics of the sample. As an example, a sample may be illuminated with infrared light having known intensity across a range of wavelengths, and the light transmitted and/or reflected by the sample can then be captured for comparison to the illuminating light. Review of the captured spectra can then illustrate the wavelengths at which the illuminating light was absorbed by the sample.
In such instruments, since a misaligned beam of captured or transmitted light may at least give rise to non-optimal instrument performance, it is usually important that the path of the light beam be carefully controlled. For example, in a Raman spectrometer—a spectrometer using laser or other monochromatic light—optical components (lasers, lenses, mirrors, etc.) along the path of the light beam generally need to be mounted within a tolerance or “capture range” of about 2 micrometers (7.913×10−5 inches), else beam misalignment will occur and operation may be impaired. Some components can be precisely aligned and then fixed in place in such a manner that they are resistant to subsequent misalignment, and adjustable mounting arrangements can be used for later “tuning” their alignment. In other cases, components are intended to be readily removable, possibly so that other components might be situated in their place—for example, a notch or band-pass filter might be removably mounted within an instrument so that it can be replaced with one or more other filters which block or accept other light wavelengths. Difficulties arise with such replaceable components because it is difficult to reproduce their desired alignment between subsequent removals and replacements, and thus it can take time to ensure the proper alignment of a component upon its installation. Mounting arrangements have been devised wherein components and/or the instrument bear placement pins or the like, such that when a component is mounted within the instrument, the pins attempt to precisely align the component. These arrangements are useful, but tend to lack the desired precision. Additionally, once a component is situated, it must often be fixed in place using fasteners (hold-down screws), latches, or similar arrangements, and these arrangements also tend to introduce variability into the component's alignment owing to the fixing forces exerted on the component and its mount. Difficulties in attaining the desired alignment are compounded by factors that tend to introduce variability in mounting precision, such as machining tolerances, surface quality/wear, environmental factors (e.g., temperature, pressure, and humidity), and of course user accuracy in effecting component placement. As a result, it can take considerable time (and can generate significant frustration) to mount an optical component within an instrument, particularly where components must be removed and replaced several times during the course of obtaining measurements.